1911 Duty Raider .45 ACP Pistol, 5.5-inch Threaded Barrel The 1911 Duty Raider is a .45 ACP pistol with a 5.5-inch threaded barrel. Duty Raider is the model designation, and the barrel measurement identifies this particular configuration rather than the pistol's overall length. A threaded barrel has a threaded muzzle interface. The presence of threads does not by itself identify their pitch or establish compatibility with a particular muzzle accessory. This version can be identified by the combination of its 1911 Duty Raider name, .45 ACP chambering and 5.5-inch barrel. Specifications Model: 1911 Duty Raider Caliber: .45 ACP Barrel Length: 5.5 inches Barrel Configuration: Threaded Shop the 1911 Duty Raider .45 ACP pistol with 5.5-inch threaded barrel at BattleHawk Armory.